Translocation of the Floral Stimulus in Xanthium

Abstract

1. The floral stimulus in Xanthium pennsylvanicum crossed an inarch contact between an induced donor plant and a receptor plant only when tissue union was established and direct tissue contact was uninterrupted for more than 4 days. 2. The floral stimulus failed to be translocated downward from an induced leaf through dead petiole tissue or through functional xylem cells. 3. The floral stimulus failed to be translocated from an induced donor branch of a two-branched plant to a receptor branch when the bark was removed from the donor branch below the induced leaves or from the receptor branch immediately above the point of branching. 4. The floral stimulus is translocated chiefly in the bark, both up and down the stem.